The present invention relates to oral hygiene appliances in general, and more particularly to improvements in apparatus for removing plaque and stains from the surfaces of teeth.
Conventional apparatus for removing plaque and stains from the surfaces of teeth have a nozzle which is manipulated by hand and has a first orifice serving to discharge a jet or stream containing a mixture of small (particularly pulverulent) solid particles and compressed air, and a second orifice which discharges a stream of water. Both streams are directed against the surface of the tooth whereby the jet or stream containing the mixture of solid particles and compressed air acts not unlike the jet which is discharged by the nozzle of a sand blasting machine. Conventional apparatus further comprise a stationary source of compressed air, a stationary supply of solid particles, and a stationary supply of pressurized water. Still further, the apparatus has a mixing chamber or vortex chamber wherein compressed air is intimately mixed with solid particles prior to entering the corresponding orifice of the nozzle, and means for connecting the nozzle with the two sources as well as with the supply of solid particles.
The vortex chamber is installed in a stationary housing for the supply of solid particles, and the corresponding connecting means includes a hose which connects the vortex chamber with the manually held nozzle. The discharge end of the hose has a coupling to allow for rapid attachment or detachment of the nozzle.
A drawback of the above outlined conventional apparatus is that the source of supply of solid material is stationary. This contributes to the bulk and cost of the apparatus. The particles of solid material contain salt and are likely to gather moisture on their way along the elongated path leading from the housing into the corresponding orifice of the nozzle. Moist particles tend to agglomerate in and to clog the hose, and particularly the nozzle. This necessitates frequent cleaning of the apparatus in order to reestablish the conditions for a predictable flow of the mixture toward and through the nozzle.